Reversing tapping device



July 14, 1925.

M. N. JARVIS REVERSING TAPPING DEVICE Filed March 21, 1923 Patented July 14, 1925.

'1 UNITED I ivrassnAnnu 1 qenv s', or G anvitasiuo 'rArri v'e Davies.

the following, when" taken in connection with the accompanying drawings and-"the characters of reference marked thereon, to

"b'e'a full, clear, and exact description of the same, and which said drawings constitute part of this application, and represent, in- Fig. -1' a: broken view,"pa1rtly :1I1 side ele- 7 vatioii and partly in vertical'section, of'one form which a reversing-j tapping device 'embodying my invention may-assume.

Fig. 2 a detachedplan 'view of the stophead and the stationary gear of the tap-revers ing train.

Fig. 3 a correspondiiig view,"sho'wing the same parts in the positions assumed by them after the shock of reversal has been absorbed, and when the train is reversing the ta). 7

Fig. 4 a detached,'perspective view of the stop-head.

Fig. 5 a corresponding view of the stationary gear of the tap-reversing train.

My invention relates to an improvement in reversing tap-ping devices, the object being to provide such devices, whatever their specific character and construict-ion, with means for absorbing the shocks developed at the instant of reversing the tap, so as to avoid breaking the same and racking the device.

lVith these ends in view, my invention consists in a reversing tapping device provided with a shock-absorber.

My invention further consists in a reversing tapping device having certain details of construction and combinations of parts as will be hereinafter described and particularly pointed out in the claims.

In carrying out my invention, as herein shown, I have applied it to a reversing tapping device, comprising a chambered body 6', a shank 7 and a chuck 8, in which latter a tap may be secured by a set-screw 10. It will be understood that, as usual in such devices, the chambered body 6 and shank 7 though not integral, are connected so as to constantly turn in the same direction, while the chuck 8 turns with themin the forward direction, but in the reverse direc- Application aiec'aviarcii 21 1923fScria1 no. 626,456.

head 15 provided'with a tubular arm tion for i'cver'sing ner by a train'of planetary gears located within the body 6 and'n'ot necessary to show or describe because HOUCOIlStltllltlIlg a part v i. a, 1,546,174 rtnnnsnEEvE, testament. I i

the tap 9. The revers- 7 ing of 'thechuck is done in the usual manof present invention, with-the singleexception of the-stationary gear 11, the conicentric' sleeve 12 of which projects upward through the body 6 I As an illustration of [a reversing tapping device of the character now being described, I refer to United States Patent No. 1,010,743, dated Decem- "ber 5', 1911, but'ly do not limit the application 'of my'invention to such a device as shown 1111116 said patent, nor tovany particular reversing tapping device;

In carrying out myinven-tion," as herein shown, the sleeve 12 of the gear 11' is'formed with two oppositely-located, wedge-shaped 'lugs 13, which enter'and have limited movement in oppositely-located, segmental notches 14,"fornied within an annular stop- 1'6and as shownin- Fig. 1, directly having bearing,

of the body 6JThe arm16 upon the flat top receives 'a stop-rodf1-7 securedin place by a pin 18 and designed -'to engage with some fixed portion of the drill-press, lathe, or other machine in which the tapping device is being used. The function of the stophead 16 andits rod 17 is to prevent the rotation of the gear 11, whereby the chuck is reversely driven in the usual manner of reversing tapping devices of the prior art.

To eliminate the shock incident to reversing the chuck and tap, and so reduce to the minimum the danger of breaking the tap and the racking of the entire device, I provide the gear 11 with the lugs 13 and the stop-head 15, with segmental notches 14 for the reception thereof, as already described. Between the notches 14, the stop-head is formed with segmental grooves 19 for the reception, respectively, of two helical, shock absorbing springs 20, each abutting at one end upon a pin 21 and having their opposite ends engaged with the faces 22 of the lugs 13, the opposite faces 24- whereof engage with the end-walls '25 of the notches 14. On the other hand, the faces 22 of the said lugs, after the compression of the springs 20, are brought to bear upon the opposite end-walls of the notches 14.

Under the construction described, the operation is as follows:

In the forward drive of the tapping deend-walls 25 of the said notches.

vice, that is to say, when the tap 9 is being threaded into the work, no operating strain is imposed upon the gear 11, nor upon the stop-head 15 and its arm 17. At this time, the faces 24 of thelugs 13 bear upon the end-walls 25 of the notches 14 against which they are lightly held by the uncompressed shock-absorbing springs 20. The instant, however, the tapping device is drawn away from the work, or the work drawn away from it, the tap-reversing train of the device is brought into play in the usual manner with the effect of almost instantly reversing the direction of rotation of the chuck 8 and tap 9. This reversing action immediately throws strain upon'the gear 11, the stophead 12 and the rod 17 whereby the said gear is oscillated within the stop-head 14 against the tension of the shock-absorbing springs, which take up the shock of this sudden reversal before the stop-faces 22 of the lugs 13 are brought to a bearing upon the Strictly speaking, the actual reversing of the chuck and tap does not begin to take place until the two springs are nearly compressed, or compressed to the limit of the compression permitted. This momentary cushioning at the time of reversal, due to the presence of the shock-absorbing springs, prevents the brittle tap from receiving what amounts to a blow at the time of reversing its movement and incidentally prevents the racking of the entire reversing mechanism.

I am aware that, broadly speaking, it is old to provide a reversing mechanism with shoclcabsorbing means for cushioning its reversing action, and do not claim such shock-absorbing reversing mechanism broad- 1y, but only asapplied, to portable reversing tapping devices.

I clalm:

1. A portable reversing tapping device having a body, a shank and a chuck, a stationary gear located within the said body ing a stop-arm and formed with an abutment, and a spring located within the said stop-head and coacting with the said lug and abutment for cushioning the shock consequent upon reversing the direction of the rotation of the chuck. I r

2. A reversing tapping device having a body, a shank and a chuck, a stationary gear located within the said body and provided with a projecting sleeve having two oppositely-locatedlugs, a stop-head carrying a stop-arm and formed with two segmental notches for the reception of the said lugs, faces of which co-act with end-walls of'the said notches, and two shock-absorbin springs located within the said stop-hea and co-acting with the said lugs for cushioning the reversing of the chuck.

In testimony whereof, I have signed this specification in the presence of two subscribing witnesses. Y

MARSHALL N. JARVIS. Witnesses:

CHARLES L. JARvIs, FRANK C. BARKER.

and provided with a lug, a stop-head carry- 

